1. Field of the Invention
The present invention relates to a permanent magnet-type magnetic adsorption device, its production method, and a magnetic apparatus.
2. Description of Prior Art
A permanent magnet-type magnetic adsorption device generally uses one or more permanent magnets and magnetically adsorbs a magnetic substance by magnetic force generated by the permanent magnet. Some of such permanent magnet-type magnetic adsorption devices are described in Patent Documents 1, 2 and 3, etc.
[Patent Document 1]
Japanese Patent Appln. Public Disclosure No. 2002-55186
[Patent Document 2]
Japanese National Public Disclosure No. 2002-518268
[Patent Document 3]
Japanese Utility Model Registration No. 3025361
All these devices include a magnetic circuit block having a cavity circular in sectional shape and having an axis extending in one direction, and a permanent magnet assembly having the N pole and S pole and disposed about the axis of the cavity so as to rotate angularly.
The magnetic circuit block is halved by a pair of spacers into a pair of magnetic pole members, but is formed integrally in appearance by welding or binding. The magnetic circuit block has an adsorption portion to adsorb a magnetic substance such as a work-piece, an iron plate, steel products, etc.
The permanent magnet assembly is made rotatable at first and second positions spaced apart about the axis. The permanent magnet assembly includes a bar-like magnetic member disposed within the cavity and at least one set of permanent magnets disposed around the magnetic members.
One of the permanent magnets of each set is attached to the magnetic member at either one of the N pole and S pole and directs the other of the N pole and S pole the inner periphery forming the cavity. The other of the permanent magnets in each set directs either one of the N pole and S pole toward the inner periphery forming the cavity, and is attached to the rotatable magnetic member at the other of the N pole and S pole.
Either one of the first and second positions is located at a position where a line of magnetic force leaks in the adsorption portion and is capable of adsorbing the magnetic substance on the adsorption portion. The other of the first and second positions is located at a position where the line of magnetic force does not leak in the absorbing portion and is incapable of adsorbing the magnetic substance on the adsorption portion.
Such a magnetic adsorption device is turned on to be capable of adsorbing the magnetic substance when the permanent magnet assembly is rotated to one of the first and second positions, and turned off to be incapable of adsorbing the magnetic substance when the permanent magnet assembly is rotated to the other of the positions.
According to a conventional permanent magnet-type magnetic adsorption device, however, since two adjoining spacers about the axis of a cavity forms an angle of 180° about the axis of the cavity, it is necessary to rotate the permanent magnet assembly to either a first position or a second position by rotating the permanent magnet assembly by 90°. For this reason, in the conventional permanent magnetic adsorption device, a range of angular rotation (angle of rotating operation) of the permanent magnet assembly required for turning the adsorption device itself on or off is great.